Metal Alloy

ABSTRACT

A metal alloy is primarily formed of copper, nickel, magnesium and iron. The main constituents are copper and nickel. The contents of magnesium and iron are increased considerably in comparison with the prior art conventional alloys.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of co-pending U.S. patent application Ser. No. 12/119,180, filed on May 12, 2008, and claims the priority, under 35 U.S.C. §119, of Austrian patent applications A 733/2007, filed May 10, 2007, and A 2091/2007, filed Dec. 20, 2007; the prior applications being herewith incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a metal alloy which essentially consists of copper, nickel, magnesium and iron. The main constituents of the alloy are copper and nickel.

Known alloys of this type have a great number of properties, on the basis of which they can be used in many technical areas and for various purposes. On account of their corrosion resistance, their mechanical strength and their ductility, they can be used in particular in the chemical industries, as well as in the oil industry, in chemical engineering and chemical apparatus construction, and in desalination technology. They can also be used for cable reinforcements, for producing spectacle frames and in many other technical areas, as well as for electrotechnical uses. Moreover, these known alloys can be used for coatings. They can also be used as welding fillers.

These known alloys are produced in the form of castings, plates, sheets, strips, foils, rods, tubes and wires, which serve as starting products for the production of many components.

In order to satisfy the requirements they have to meet when they are used, these metal alloys must have good processing properties, that is to say they must allow good casting and cold and hot forming, must also allow for good welding and good soldering or brazing, must allow good machining, good grinding and polishing and also allow themselves to be electroplated.

All these requirements are met for example by the NiCu30Fe alloy material No. 2.4360 in accordance with DIN 17743. That known alloy has the following constituents in the proportions given below (in % by mass and/or % by weight):

nickel at least 63% copper 28% to 34% iron 1% to 2.5% manganese at most 2% other materials at most 1%

One of the reasons for the good material properties explained above is that the individual alloying constituents are completely soluble in one another, whereby they form a closed solid-solution series with no miscibility gaps and as a result of which the alloy is completely homogeneous within itself.

The prior art metal alloy and similar further nickel-copper alloys have very high proportions of nickel, which must be taken into consideration because the world market price of nickel is many times higher than the price of copper, for which reason these known alloys are very expensive. Likewise known copper-nickel alloys with low nickel contents and only small additions of further alloying elements have in turn poorer properties, for example with regard to mechanical strength and ductility or with regard to their corrosion resistance in aggressive media.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a metal alloy, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for an alloy which has the same advantageous properties as the prior art alloys, in particular as the alloy NiCu30Fe, but which however contains a much reduced proportion of nickel in comparison with the latter, as a result of which it is significantly less expensive than the known alloy. In particular, the alloy of the instant invention shares, among other advantages of the NiCu30Fe, the advantage that the individual alloying constituents of the invention are completely soluble in one another, whereby they form a closed solid-solution series with no miscibility gaps, a result of which is that the inventive alloy is also completely homogeneous within itself.

With the foregoing and other objects in view there is provided, in accordance with the invention, a copper-nickel metal alloy that is primarily formed of copper, nickel, manganese and iron. The main constituents are copper and nickel. The contents of manganese and iron are increased considerably in comparison with the prior art conventional alloys. The novel alloy according to the invention has the following constituents in the following proportions (in % by mass and/or wt. %):

copper 40% to 61% nickel 35% to 45% manganese 3.9% to 10% iron 0.1% to 5% other materials (e.g., carbon, at most 2% in total silicon, aluminum, magnesium, titanium, chromium, rare earths, molybdenum, yttrium) with the sum of the individual components adding to 100% by mass or 100% by weight.

On account of its much lower proportion of nickel, this alloy is significantly less expensive than the known nickel-copper alloys, without its properties being made any worse than the known alloys. On account of the much higher proportion of manganese in comparison with the prior art, this alloy also has particularly high heat resistance, which is required for many applications.

This alloy preferably has the following proportions (in % by mass and/or % by weight):

copper 46% to 59% nickel 37% to 42% manganese 3.9% to 7% iron 0.2% to 5% other materials at most 2% in total. with the sum of the selected components adding to 100% by mass or 100% by weight.

A specific preferred alloy has the following constituents in the following proportions (in % by mass or wt. %):

copper 55.03% nickel 39.66% manganese 4.64% iron 0.46% carbon 0.05% silicon 0.06% aluminum 0.02% magnesium 0.03% titanium 0.01% chromium 0.02% other materials 0.02%

A further preferred alloy has the following constituents in the following proportions (in % by mass and/or % by weight):

copper 52.87% nickel 39.16% manganese 3.98% iron 3.75% carbon 0.05% silicon 0.09% aluminum 0.03% magnesium 0.03% titanium 0.01% chromium 0.02% other materials 0.01%

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is described herein as embodied in metal alloy, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of the four alloys representing specific embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION Example 1

In this example the alloy has the following constituents in the following proportions (in % by mass and/or % by weight):

copper 40% to 61% nickel 35% to 45% manganese 3.9% to 10% iron 0.1% to 5% other materials, such as carbon, at most 2% in total silicon, aluminum, magnesium, titanium, chromium, rare earths, molybdenum, yttrium with the sum of the selected components adding to 100% by mass or 100% by weight.

Example 2

In this example the alloy has the following constituents in the following proportions (in % by mass and/or % by weight):

copper 46% to 59% nickel 37% to 42% manganese 3.9% to 7% iron 0.2% to 5% other materials, such as carbon, at most 2% in total silicon, aluminum, magnesium, titanium, chromium, rare earths, molybdenum, yttrium with the sum of the selected components adding to 100% by mass or 100% by weight.

Example 3

In this example the alloy has the following constituents in the following proportions (in % by mass and/or % by weight):

copper 55.03% nickel 39.66% manganese 4.64% iron 0.46% carbon 0.05% silicon 0.06% aluminum 0.02% magnesium 0.03% titanium 0.01% chromium 0.02% other materials 0.02%

Example 4

In this example the alloy has the following constituents in the following proportions (in % by mass and/or % by weight):

copper 52.87% nickel 39.16% manganese 3.98% iron 3.75% carbon 0.05% silicon 0.09% aluminum 0.03% magnesium 0.03% titanium 0.01% chromium 0.02% other materials 0.01%

All of these alloys have a comparatively high proportion of copper and a comparatively low proportion of nickel, as a result of which they are comparatively low in cost in comparison with known Ni—Cu alloys on account of the considerable difference in the price of nickel and copper. Quite apart from this, these alloys are highly corrosion-resistant, have high strengths and can be processed very well on account of their very homogeneous structure, as a result of which they can be used in a wide variety of areas. In particular, the individual alloying constituents of the foregoing alloys of examples 1-4 are completely soluble in one another, whereby they form a closed solid-solution series with no miscibility gaps, one result of which is that the alloy is completely homogeneous within itself.

For example, in comparison with NiCu30Fe, the alloy according to Example 3 and the alloy according to Example 4 have under the same processing conditions in rolling, drawing, intermediate annealing and final annealing very similar mechanical values on round and flat products, which has very favorable effects on their processability: in Table 1 below, the tensile strengths Rm (in N/mm²) and the elongation to fracture A200 (in %, based on a measured length of 200 mm) are compared between the alloy according to Example 3, the alloy according to Example 4 and the known alloy NiCu30Fe, in each case in the form of round wire of 1.80 mm in diameter and flat wire of 12.7×0.38 mm, both soft-annealed.

TABLE 1 Round wire Flat wire Rm (N/mm²) A200 (%) Rm (N/mm²) A200 (%) Alloy according to 561 34 533 29 Example 3 Alloy according to 576 33 547 28 Example 4 Alloy NiCu30Fe 547 34 525 29

The mechanical values of all three alloys compared are to be considered as the same within the usual batch-dependent variations. Similarly, for example, the stability with respect to softening during brazing at temperatures of 600° C. and above is to be considered as equally good, much better than in the case of copper-nickel alloys without these high manganese and iron contents.

The alloys of Example 3 and Example 4 exhibiting the properties discussed in connection with Table 1 were produced using certain common process parameters and production steps. For example, in the production of both of Example 3 and Example 4, there was a common smelting of the individual alloying constituents of defined composition at a temperature in the range of 1420-1520° C., i.e. 100-200° C. above the liquidus line, wherein the smelting process is completed. Subsequently, the alloy of Examples 3 and 4 were cast at 1320-1420° C. into the shape of an ingot with 1.5 tons of weight, about 1.5 meters (9 feet) in height and 30 to 40 cm (11.81-15.75 inches) in width. The alloys were then hot rolled at a temperature in the range of 1030-1150° C. from the ingot, into 2 or 3 billets having a 120 to 135 mm (4.72-5.31 inch) dimension. The resulting work product of the hot rolling step was ground on all 4 sides to a weight loss of 5-10%, followed by an ultrasonic inspection with regard to non-metallic inclusions larger than 1 mm (0.04 inches) in size. After grinding, the result product is hot rolled a second time in a second heating step from the billet into a black, oxidized, round wire rod of 5.5-7.5 mm (0.22-0.30 inches) in diameter. The second hot rolling was performed at a temperature range of 1000-1080° C.

The black, oxidized, round wire rods at the hot rolling temperature were then quenched in water. Such quenching is a common process step and is also performed in the production of NiCu30Fe wire rods of the same size. The quenched rods were then stationary annealed in a bell furnace at 700° C., in an atmosphere containing 1.5-3.0% H₂ and 98.5-97.0% N₂. The annealed wire rods were then pickled in hydrochloric acid for 1 hour, as is also done with the NiCu30Fe wire rods. Subsequent to pickling, the rods were cold-worked by cold-drawing or cold rolling the 5.5-7.5 mm wire rods to round or flat wire employing area-reductions and intermediate annealing steps, as is also done for NiCu30Fe wire, even to the point of using the same lubricants and detergents used in the production of the known NiCu30Fe wire. The round and flat wires so produced, having achieved their final dimensions, were then subjected to a final annealing step in a continuous furnace with an atmosphere of 90% N₂ and 10% H₂ at 950° C. at the same line speeds as used for wires made from the known NiCu30Fe alloy of the same dimensions.

It is important to note that the production parameters and method for producing the homogenous copper-nickel wrought alloy of the foregoing Examples 3 and 4, described hereinabove, are the same as for the production of NiCu30Fe alloy, which fact is important for the users of the homogenous copper-nickel alloy wrought in accordance with the instant invention. In particular, by using the same production parameters for the homogenous copper-nickel wrought alloy of the present invention, very similar properties to those of the known NiCu30Fe alloy can be achieved by the alloy of the invention, for example, by the alloy of Examples 3 and 4.

In order to achieve these properties with the alloy of the instant invention, it is relevant that the individual alloying constituents are heated up to their molten status and that the individual alloying constituents become soluble in one another to form a closed solid-solution series with no miscibility gaps. As a result thereof the manufactured copper-nickel wrought alloy in accordance with the instant invention is homogenous within itself. It is a wrought alloy cast from a fully liquid melt; it is not a singered metal produced by sintering together powder particles and grains by diffusion processes performed at lower temperatures than the melting temperatures of the constituents.

A further example of the comparatively good properties of the alloys produced according to Example 3 and according to Example 4, in comparison with alloys with a higher nickel content, is the comparatively good corrosion behavior of the alloys according to Example 3 and according to Example 4 as compared with NiCu30Fe. The results of two comparative corrosion tests are given below:

a) Test in 62% CaCl₂ at 120° C. for 5 days:

The loss in weight (g/m² h) in the case of NiCu30Fe is 0.010, in the case of the alloy according to Example 3 it is 0.014, i.e., the alloy according to Example 3 is approximately 71% as corrosion resistant under these conditions as NiCu30Fe, with a nickel content of about 59% in comparison with NiCu30Fe, and, like NiCu30Fe, also shows no signs of harmful pitting.

b) Test in 27 g/l of NaCl at 80° C., 6 bar H₂S, 6 bar CO₂ for 14 days:

The loss in weight (g/m² h) in the case of NiCu30Fe is 0.0186, in the case of the alloy according to Example 4 it is 0.0100, i.e. the alloy according to Example 4 is approximately 186% (that is almost twice) as corrosion resistant under such conditions as NiCu30Fe, with a nickel content of about 59% in comparison with NiCu30Fe, and, in the same way as NiCu30Fe, also shows no signs of harmful pitting. 

1. A homogenous copper-nickel metal alloy, consisting essentially of the following constituents in the following proportions (in % by mass and/or % by weight): copper 40% to 61% nickel 35% to 45% manganese 3.9% to 10% iron 0.1% to 5% other materials at most 2% in total

with the sum of the selected components adding to 100% by mass or 100% by weight; and the individual alloying constituents being completely soluble in one another to form a closed solid-solution series with no miscibility gaps, such that the alloy is completely homogenous within itself.
 2. The metal alloy according to claim 1, consisting of copper, nickel, manganese, iron, and other materials in the following proportions (in % by mass and/or % by weight): copper 55.03%  nickel 39.66%  manganese 4.64% iron 0.46% other materials  0.21%.


3. The metal alloy according to claim 2, wherein said other materials are present in the following proportions (in % by mass and/or % by weight of the total alloy): carbon 0.05% silicon 0.06% aluminum 0.02% magnesium 0.03% titanium 0.01% chromium 0.02% further materials 0.02%


4. The metal alloy according to claim 3, wherein said further materials are selected from the group consisting of the rare earths, molybdenum, and yttrium.
 5. The metal alloy according to claim 1, consisting of copper, nickel, manganese, iron, and other materials in the following proportions (in % by mass and/or % by weight): copper 52.87%  nickel 39.16%  manganese 3.98% iron 3.75% other materials  0.24%.


6. The metal alloy according to claim 5, wherein said other materials are present in the following proportions (in % by mass and/or % by weight of the total alloy): carbon 0.05% silicon 0.09% aluminum 0.03% magnesium 0.03% titanium 0.01% chromium 0.02% further materials  0.01%.


7. The metal alloy according to claim 6, wherein said further materials are selected from the group consisting of the rare earths, molybdenum, and yttrium. 